Highway stormwater runoff in karst areas—preliminary results of baseline monitoring and design of a treatment system for a sinkhole in Knoxville, Tennessee

摘要

Groundwater is vulnerable to contamination inkarst areas where higheay stormwater runoff may flow directlyinto karst aquifers with little or no natural attenuation andtransport highway-derived contaminants rapidly from sinkholesto locations in the aquifer. The primary goal of this investigationis the development and evaluation of practical remedial measuresfor treating highway runoff draining into sinkholes. Field testingsites are located in Knoxville, TN, and Frederick, MD. This paperpresents a summary of preliminary results of baseline monitoringin Knoxville. Quantitative dye tracing and hydrograph analyseshave demonstrated that water draining into the I-40/I-640sinkhole passes through a phreatic conduit and resurges atHolston Spring ca 128 m (420 ft) from the sinkhole. Stormwaterquantity has been monitored continuously for more than 1.5 years,and runoff quality has been monitored during a storm event. Formost of the contaminants analyzed, peak contaminant loading atHolston Spring lagged behind the peak at the sinkhole byapproximately 1 hour. The movement of stormwater from othersinkholes in the drainage basin to Holston Spring is regulated bypartial blockage of the conduit-dominated flow system. Urbandevelopment of the karst terrane in eastern Knoxville may beresponsible for this observed phenomenon. A pilotscalestormwater runoff treatment system has been designed using peat,sand, and rock to remove contaminants by sedimentation,filtration, and adsorption.